1. Field of the Invention
The present invention relates to a hydrogenated copolymer. More particularly, the present invention is concerned with a hydrogenated copolymer obtained by hydrogenating an unhydrogenated copolymer comprising conjugated diene monomer units and vinyl aromatic monomer units, the hydrogenated copolymer comprising:
at least one polymer block selected from the group consisting of a polymer block (A) of vinyl aromatic monomer units, and a hydrogenated polymer block (C) which is obtained by hydrogenating an unhydrogenated polymer block of conjugated diene monomer units, wherein the unhydrogenated polymer block of conjugated diene monomer units has a specific vinyl bond content, and
at least one hydrogenated copolymer block (B) which is obtained by hydrogenating an unhydrogenated random copolymer block comprised of conjugated diene monomer units and vinyl aromatic monomer units,
wherein, when the hydrogenated copolymer contains no hydrogenated polymer block (C), the hydrogenated copolymer contains at least two polymer blocks (A),
wherein the hydrogenated copolymer has a specific content of the vinyl aromatic monomer units, a specific content of the polymer block (A), a specific weight average molecular weight, a specific hydrogenation ratio as measured with respect to the double bonds in the conjugated diene monomer units, a characteristic that at least one peak of loss tangent (tan δ) is observed at −10 to 80° C. in a dynamic viscoelastic spectrum obtained with respect to the hydrogenated copolymer, and a characteristic that, when the hydrogenated copolymer contains no hydrogenated polymer block (C), substantially no crystallization peak ascribed to the at least one hydrogenated copolymer block (B) is observed at −20 to 80° C. in a differential scanning calorimetry (DSC) chart obtained with respect to the hydrogenated copolymer.
The hydrogenated copolymer of the present invention has excellent properties with respect to flexibility, tensile strength, abrasion resistance, anti-impact scratch property and crosslinkability.
The present invention is also concerned with a first-order modified, hydrogenated copolymer obtained by modifying the hydrogenated copolymer, and a second-order modified, hydrogenated copolymer obtained by modifying the first-order modified, hydrogenated copolymer. The first-order modified, hydrogenated copolymer and the second-order modified, hydrogenated copolymer have excellent properties with respect to flexibility, tensile strength, abrasion resistance, anti-impact scratch property, adhesion properties and crosslinkability.
Further, the present invention is also concerned with a hydrogenated copolymer composition comprising the hydrogenated copolymer and at least one polymer selected from the group consisting of a thermoplastic resin and a rubbery polymer (hereinafter, the at least one polymer is frequently referred to as “component (b)”); a first-order modified, hydrogenated copolymer composition comprising the first-order modified, hydrogenated copolymer and the component (b); and a second-order modified, hydrogenated copolymer composition comprising the second-order modified, hydrogenated copolymer and the component (b).
The hydrogenated copolymer of the present invention, the first-order modified, hydrogenated copolymer of the present invention, the second-order modified, hydrogenated copolymer of the present invention, the hydrogenated copolymer composition of the present invention, the first-order modified, hydrogenated copolymer composition of the present invention, and the second-order modified, hydrogenated copolymer composition of the present invention are advantageous not only in that they are suitable for use as a foaming material, a building material, a vibration damping, soundproofing material, an electric wire coating material and the like, but also in that, when they are subjected to a crosslinking reaction in the presence of a crosslinking agent, there can be obtained crosslink products having excellent properties with respect to abrasion resistance, heat resistance and the like. Further, the hydrogenated copolymer of the present invention, the first-order modified, hydrogenated copolymer of the present invention, and the second-order modified, hydrogenated copolymer of the present invention can be advantageously used in an adhesive composition, an asphalt composition and the like.
2. Prior Art
With respect to a block copolymer comprising conjugated diene monomer units and vinyl aromatic hydrocarbon monomer units, when the vinyl aromatic hydrocarbon monomer unit content thereof is relatively low, the block copolymer exhibits, even if not vulcanized, not only excellent elasticity at room temperature, which is comparable to that of a conventional, vulcanized natural or synthetic rubber, but also excellent processability at high temperatures, which is comparable to that of a conventional thermoplastic resin. Therefore, such a block copolymer having a relatively low content of vinyl aromatic hydrocarbon monomer units is widely used in various fields, such as the fields of footwear, modifiers for plastics, modifiers for asphalts, and adhesive agents.
On the other hand, when the block copolymer comprising conjugated diene monomer units and vinyl aromatic hydrocarbon monomer units has a relatively high content of vinyl aromatic hydrocarbon monomer units, the block copolymer is a thermoplastic resin having excellent properties with respect to transparency and impact resistance. Therefore, such a block copolymer having a relatively high content of vinyl aromatic hydrocarbon monomer units can be advantageously used in various fields, such as the fields of packaging containers for food, packaging materials for household goods, packaging materials for household electric appliances, packaging materials for industrial parts, and toys.
Further, a hydrogenation product of the above-mentioned block copolymer has excellent weathering resistance and excellent heat resistance, so that the hydrogenation product is advantageously used not only in the above-mentioned various fields, but also in the fields of automobile parts, medical equipment and the like.
However, the above-mentioned block copolymer is disadvantageous in the following points. When the block copolymer has a relatively low content of vinyl aromatic hydrocarbon monomer units, although the block copolymer has excellent flexibility, the block copolymer has poor abrasion resistance, thus rendering it difficult to broaden the range of use of such a block copolymer. On the other hand, when the block copolymer has a relatively high content of vinyl aromatic hydrocarbon monomer units, the block copolymer has poor flexibility and, hence, is unsuitable for use as a flexible material.
With respect to a random copolymer comprising conjugated diene monomer units and vinyl aromatic hydrocarbon monomer units, it has been attempted to cause the random copolymer to exhibit excellent flexibility. For example, Unexamined Japanese Patent Application Laid-Open Specification No. Hei 2-158643 (corresponding to U.S. Pat. No. 5,109,069) discloses a composition containing a hydrogenated diene copolymer and a polypropylene resin, wherein the hydrogenated diene copolymer is obtained by hydrogenating a random copolymer which comprises conjugated diene monomer units and ylnyl aromatic hydrocarbon monomer units and which has a vinyl aromatic hydrocarbon monomer unit content of from 3 to 50% by weight, a molecular weight distribution of 10 or less (wherein the molecular weight distribution means the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn)), and a vinyl bond content of from 10 to 90% as measured with respect to the conjugated diene monomer units in the random copolymer. Further, Unexamined Japanese Patent Application Laid-Open Specification No. Hei 6-287365 discloses a composition containing a hydrogenated diene copolymer and a polypropylene resin, wherein the hydrogenated diene copolymer is obtained by hydrogenating a random copolymer which comprises conjugated diene monomer units and vinyl aromatic hydrocarbon monomer units and which has a vinyl aromatic hydrocarbon monomer unit content of from 5 to 60% by weight and a vinyl bond content of 60% or more as measured with respect to the conjugated diene monomer units in the random copolymer.
Meanwhile, with respect to the hydrogenated diene copolymers contained in the compositions disclosed in the above-mentioned patent documents, it has been attempted to use the hydrogenated diene copolymers as substitutes for a flexible vinyl chloride resin. The flexible vinyl chloride resin causes various environmental problems, such as generation of halogen gas when the resin is burned, and generation of environmental hormones due to the plasticizer used in the resin. Therefore, there is a pressing need for development of a substitute material for the flexible vinyl chloride resin. However, the above-mentioned hydrogenated diene copolymers have unsatisfactory properties with respect to abrasion resistance, anti-impact scratch property and the like which are important for a material used as a substitute for the flexible vinyl chloride resin.
In recent years, it has been attempted to cause the above-mentioned block copolymer comprising conjugated diene monomer units and vinyl aromatic hydrocarbon monomer units and having a relatively high content of vinyl aromatic hydrocarbon monomer units, to exhibit excellent flexibility.
For example, Japanese Patent Application Prior-to-Examination Publication (Tokuhyo) No. Hei 10-501833 (corresponding to U.S. Pat. No. 6,031,053) discloses a block copolymer comprising a conjugated diene polymer block and a conjugated diene/vinyl aromatic hydrocarbon copolymer block. However, this block copolymer has unsatisfactory abrasion resistance.
On the other hand, Unexamined Japanese Patent Application Laid-Open Specification No. Hei 2-300250 discloses a block copolymer comprising a conjugated diene polymer block and a vinyl aromatic hydrocarbon polymer block, wherein the conjugated diene polymer block comprises only isoprene monomer units or a mixture of isoprene monomer units and butadiene monomer units and has a total content of 3,4-vinyl bonds and 1,2-vinyl bonds of 40% or more, and wherein at least one peak of loss tangent (tan δ) is observed at 0° C. or more in a dynamic viscoelastic spectrum obtained with respect to the block copolymer. However, this block copolymer has unsatisfactory abrasion resistance.
WO98/12240 (corresponding to GB 0927210) discloses a molding material comprised mainly of a hydrogenated block copolymer which is obtained by hydrogenating a block copolymer comprising a polymer block comprised mainly of styrene monomer units and a copolymer block comprised mainly of butadiene monomer units and styrene monomer units. Further, Unexamined Japanese Patent Application Laid-Open Specification No. Hei 3-185058 discloses a resin composition comprising a polyphenylene ether resin, a polyolefin resin, and a hydrogenation product of a vinyl aromatic/conjugated diene random copolymer, wherein the hydrogenation product of a vinyl aromatic/conjugated diene random copolymer is substantially the same as the hydrogenated block copolymer used in the above-mentioned WO98/12240. However, any of the hydrogenated copolymers described in the above-mentioned patent documents has poor flexibility and, hence, is not suitable for use as a substitute for the flexible vinyl chloride resin.
Thus, although there has been a pressing need for development of a substitute material for the flexible vinyl chloride resin, which poses various environmental problems, there has not yet been obtained a material having desired properties (such as excellent flexibility and excellent abrasion resistance) which are comparable to those of the flexible vinyl chloride resin.